In many conventional electric motors, a rotating magnetic field is produced by passing an electrical current through a main winding formed about a stator to torque a rotor rotationally. A start winding can be included within the stator assembly of the motor to produce the rotating magnetic field with sufficient torque to begin rotation of the rotor. Once the rotor approaches its predetermined operational speed, a switch responsive to the rotational speed of the motor is opened to remove the electrical current from the start winding. Upon the motor speed slowing below another predetermined speed of operation from, for example, load conditions on the motor or shut down of the motor, the switch closes so electrical current can energize the start winding of the motor again.
One known switch used to apply and then remove electrical current from a start winding is a centrifugal actuator switch. The contacts of the switch are initially closed to enable electrical current to flow through the main and start windings of the electrical motor. The switch has a bracket, which is fixedly mounted about the output shaft of the motor, so the switch rotates with the rotor. A sleeve is mounted above the bracket for axial movement along the bracket on the output shaft. A pair of weighted levers is pivotally mounted on the sleeve. As the rotational speed of the bracket on the output shaft approaches the predetermined operational speed, centrifugal force produced by the rotation of the output shaft and bracket causes the weights to pivot on the sleeve. The pivoting of the weighted levers shifts the sleeve axially along the bracket and the output shaft of the motor. This axial movement of the sleeve from an initial, sometimes known as the starting, position to a second, sometimes called a run, position as the rotational speed of the output shaft accelerates to its predetermined operational speed, opens the contacts of the switch to terminate the flow of electrical current through the start winding, while electrical current continues to flow through the main winding through another set of contacts in the switch. The lever arms are biased towards one another by a pair of springs mounted on diametrically opposite sides of the sleeve. One end of each spring is attached to a lever hook extending from one of the weighted levers on diametrically opposed sides of the sleeve and the other end of each spring is similarly attached to a lever hook extending from the other weighted arm at a diametrically opposed side of the sleeve. As the rotational speed of the output shaft slows, the centrifugal force acting on the weighted levers is reduced and the springs pull the lever arms towards each other so they pivot and return to their starting position, which causes the sleeve to return to its starting position on the bracket for the next start-up of the motor.
Some electrical motors are used in common appliances. For example, clothes dryers and washers use an electrical motor to rotate a drum in which wet clothes are placed for drying or washing, respectively. The motors in these appliances typically include a centrifugal actuator switch to start the motor and then remove electrical power from the start winding as described above. Vibrations arising from unbalanced loads and other conditions can subject the motors and related components, such as the centrifugal actuator switch, to significant stresses. One problem arising from these vibrations is movement of the ends of the springs biasing the lever arms of the centrifugal actuator switch against the lever hooks on the weighted levers. The resulting rubbing of the spring material against the lever hooks can cause the end of the spring or the end of the lever hook to break and release the biasing force. As a consequence, the switch no longer performs reliably and the motor is unable to start. Therefore, constructing a centrifugal actuator switch capable of better withstanding the stresses arising from vibrations in the motor is desirable.